Commuting daily across border: Where taxable

[worryfreeinvestor]

I have not quite seen this situation in the threads:

Joe is a citizen of Canada and a citizen of the U.S. He lives in Blaine, WA and works as an independent contractor for a firm in Surrey, BC. The firm pays him gross. He goes that office (in Canada) to work.

To be clear: Every night, he sleeps in Blaine, WA. He drives through the Peace Arch border crossing to Surrey, BC, every morning, Monday through Friday. He drives back into the U.S. every evening.

In which country is he taxable as a resident?

[nelsona]

He is taxable as a resident and citizen of US, of course, and all income is reportable there.

The question is whether the Cdn income is taxable in Canada or not. It comes down to the number of DAYS he spends in Canada, in ANY 365 day period (not simply calendar year). If it is more than 183 days in that period, the Cdn income is taxable in Canada.
Based on what you say, the income is taxable in Canada, and a non-resident tax return needs to be filled to determine the CDn tax, and then that income and tax will determine the crdit you receive on your 1040. You should be paing US SE tax on this money (and not Cdn CPP).

You are a resident of US, but the time you are spending in Canada is making your business income taxable there, by the latest treaty.